PurposeThis study investigates whether the Police Reform Bill significantly reduced overall incidents of police misconduct, including those involving the use of force, in Massachusetts. MethodsThe current study employed a monthly interrupted time series (ITS) design using data on overall incidents of police misconduct and incidents involving the use of force, collected from the 438 law enforcement agencies in Massachusetts. The Police Reform Bill was introduced in December 2020. The monthly data covers the period from January 1989 through December, 2023 (N = 420), with January 1989 through December 2021 serving as the period before the implementation of the Police Reform Bill (N = 384) and January 2022 through December, 2023 as the period following the implementation of the Police Reform Bill (N = 36). ResultsThe results of the monthly interrupted time series analyses showed that, compared to before the implementation of the Police Reform Bill, the trend in the overall number of police misconduct incidents and the number of misconduct incidents involving the use of force significantly declined after the implementation of the Police Reform Bill. ConclusionsThe findings suggest that the Police Reform Bill is effective in reducing police misconduct and misconduct incidents involving the use of force.